Plate for use in lining burglarproof vaults and similar purposes



Aug. 7, 1923. l,464.102

F. J. NAPOLITAN PLATE FOR USB IN LINING BURGLARPROOF VAULTS AND SIMILAR PURPOSES Filed Aug. 15. 1921 Patented Aug. 7, 1923.

UNITED STATES PATENT OFFICE.

FRANCIS JU NAPOLITAN, OF JERSEY CITY, NEW JERSEY, ASSIGNOR TO AMERICAN ABRASIVE METALS COMPANY, A CORPORATION OF NEW YORK.

PLATE FOR USE IN LINING BURGLARPROOF VAULTS AND SIMILAR PURPOSES.

Application filed August 13, 1921.

TO all w kom it may concem Be it known that I, F RANCIS J. NAPoLI- TAN, a citizen of the United States of America, residing at Jersey City, county of Hudson, State of New Jersey, with "a postoflice address at 51 Tonnele Ave., Jersey City, N. J., have invented certain new and useful Improvements in Plates for Use in Lining Burglarproof Vaults and Similar Purposes, of which the following is a specification.

My invention relates to the production of plates which shall have the highest attainable resistance to the action of an oxyacetylene burner or similar cutting torch, and at the same time be resstant to cutting tools. Plates of this character are particularly useful in lining bank vaults and safes liable to be attackecl by burglars using oxy-acetylene torches in the effort to penetrate to the interior of the structure, but can be employed to advantage in other situations.

The rapid penetration of an ordinary metallic plate operated on by a cutting torch of the above mentioned character is due primarily to the fact that after the heat of the fiame of oxy-acetylene (or other combustible gas) has raised the metal on which the flame impinges to a certain temperature that metal thereafter combines directly with a special high pressure jet of oxygen, also directed against it, such combination causing a rapid disintegration of the material so attacked and reducing the previously solid structure of the plate to a molten oxide which flows away, and secondarily to the fact that such molten oxide before escaping is driven against the disintegrating surface of the plate with great physical force by the high pressure oxygen jet and exercises an acute eroding action on such surface. Finally, in eventually flowing away from the point of attack over the adjacent surface of the plate, the molten oxide gives back by conduction a large part of its heat to the plate at the point of attack, thus further assisting in its disintegration. Both Chemical and physical reactions are therefore to an extent self propagating and regenerative, and their combined effects will bore a hole through an iron plate with great rapidity.

Serial No. 192,201.

Ferrous metals are particularly Weak before the attack of such a cutting torch because such metals combine with oxygen at the high temperature involved, with great av1dity. The oxides also have great solvent or erosve power on the remaining iron, and a greater oxidizing action on it than has pure oxygen itself. This eroding and oxdizng action of iron slag is also effectve on other metals so that it is common practice in cutting with a torch nickel and other metals not reaclily oxidized, to feed a small iron rod into the torch fiame so that iron sla may be formed and driven against the nickel or other metal body. Iron, however, is a desirable constituent, in practice, in the making of vault and safe hnings because of its great structural strength combined with cheapness and with ease of working. I have found, therefore, that the best form of plate embodying my invention should have a body or matrix of cast iron in which are embedded closely packecl masses of some other material having a high melting point, a hi h state of oxdaton and a high degree of resistance to erosion by the iron slag which will be formed by oxidation of the iron matrix. This embedded material should also' be characterized by freedom from hydrates or contained water so as not to decrepitate on heating, and by as much structural strength and hardness which gives resistance to cutting tools, as possible. Other metallic materials may, however, be used for the matrix in some cases.

I have discovered that magnesium oxide, fused and crystallized, possesses to a high degree the qualities above recited as requisite to resist the action of the cutting torch. It is highly refractory, having a melting point of approximately 2800 degrees centigrade. It is in the highest state of oxi daton; when fused or otherwise crystallized it is resistant to erosion. It is not easily dissolved by molten iron slag. When made by' fusion it is not readily hydrolyzed, so that it forms no hydrate. Its true crystalline form is regular or hexagonal, this characteristic giving it a minimum possibilty of cleavage, and consequently produc ing relatively high structural strength.

In the accompanyng drawing I have shown in cross section a plate made in accordance with this embodiment of my invention.

1 represents the matrix of cast metallic material and 2, 2 represent masses of fused magnesium oxide cast and embedded therein in the form of graded aggregate, the smaller particles filling the voids between the larger ones sufliciently to make it impossible for a torch fiame or drill to pass through the plate without striking one or more of these bodies of fused magnesium oxide.

The magnesium oxide is fused, and perhaps re-fused, in an electric furnace so as properly to crystallize it and free it from mpurities, and then broken up into smaller masses by hammering or other suitable treatment.

While fused magnesium oxlde masses prepared and employed as above described, have the highest possible power of resistance to a cutting torch, they do not present an equally great resistance to cutting tools. In some instances it may be advantageous to sacrifice a little of the power of resistance to the cutting torch to secure an added degree of resistance to drlls or other cutting tools in the composite plate. I have found that this compromise result can best be efiected by using an artificial spinelle in place of the pure fused magnesium oxide. This spinelle is a fused mixture of aluminum oxide and magnesium oxide. On fusing these together and permitting them to crystallize they form an eutectic mixture or solid solution of definite proportions. The magnesium oxide is added in excess so that the excess is rejected from crystals of the spinelle as the mass cools. The magnesium oxide is thus added in excess because it imparts a greater resistance to the action of the cutting torch than does the aluminum oxide. The aluminum oxide in the eutectio mixture is, however, more resistant to' cutting tools than is magnesium oxide,

being nearly as hard as the diamond. I thus add its good qualities, in this regard, to the torch-resisting qualities ofthe magnesium oxide, and while the fusing point of the eutectic mixture is slightly lower than that of the pure magnesium oxide, the contained crystals of the latter give full resistance to the torch.

Having described my nvention I claim:

1. As a new article of manufacture a plate for use in forming bank vaults and similar purposes which plate comprses a matrix of cast iron in which are embedded closely packed masses each comprising fused and crystallized magnesium oxide substantially free from hydrates and in the form of a graded aggregate.

2. As a new article of manufacture a plate for use in forming bank vaults and similar purposes, which plate comprises a matrix of cast metallic material in which are embedded closely packed masses, each comprising a fused and crystallized, highly refractory material in a high state of oxidation, substantially free from hydrates.

3. As a new article of manufacture a plate for use in forming bank vaults and similar purposes, which plate comprises a matrix of cast metallic material in which are embedded closely packed masses, each comprisng a fused and crystallized, highly refractory material in a high state of oxidation.

4. As an article of manufacture a plate for use in forming bank vaults and similar purposes, which plate comprises a matrix of cast metallic material in which are embedded closely packed masses each consisting of a fused and crystallized eutectic mixture of magnesium oxide and aluminum oxide with magnesium oxide in excess.

5. As an article of manufacture a plate for use in forming bank vaults and similar purposes, which plate comprises a matrix of cast metalli material in which are embedded closely packed masses each consisting of a fused eutectic mxture of magnesium oxide and aluminum oxide with magnesium oxide in excess.

6. As as article of manufacture a plate for use in forming bank vaults and similar purposes, which plate comprises a matrix o' cast metallic material in which are embedded closely packed masses each consisting of a fused and crystallized mixture of magnesium oxide and aluminum oxde.

7. As a new article of manufacture, a safe or vault plate formed of cast metal flowed around and encasing irregularly 'disposed lumps of refractory magnesium oxide.

8. As a new article of manufacture, a`

safe or vault plate formed of cast metal flowed around and encasing irregularly' 

